Sulfonated carbons were explored as functionalized supports for Ni nanoparticles to hydrodeoxygenate (HDO) phenol. Both hexadecane and water were used as solvents. The dual-functional Ni catalysts supported on sulfonated carbon (Ni/C-SO₃H) showed high rates for phenol hydrodeoxygenation in liquid hexadecane, but not in water. Glucose and cellulose were precursors to the carbon supports. Changes in the carbons resulting from sulfonation of the carbons resulted in variations of carbon sheet structures, morphologies and the surface concentrations of acid sites. While the C-SO₃H supports were active for cyclohexanol dehydration in hexadecane and water, Ni/C-SO₃H only catalysed the reduction of phenol to cyclohexanol in water. The state of 3–5 nm grafted Ni particles was analysed by in situ X-ray absorption spectroscopy. The results show that the metallic Ni was rapidly formed in situ without detectable leaching to the aqueous phase, suggesting that just the acid functions on Ni/C-SO₃H are inhibited in the presence of water. Using in situ IR spectroscopy, it was shown that even in hexadecane, phenol HDO is limited by the dehydration step. Thus, phenol HDO catalysis was further improved by physically admixing C-SO₃H with the Ni/C-SO₃H catalyst to balance the two catalytic functions. The minimum addition of 7 wt % C-SO₃H to the most active of the Ni/C-SO₃H catalysts enabled nearly quantitative conversion of phenol and the highest selectivity (90 %) towards cyclohexane in 6 h, at temperatures as low as 473 K, suggesting that the proximity to Ni limits the acid properties of the support.

The role of the specific physicochemical properties of ZrO₂ phases on Ni/ZrO₂ has been explored with respect to the reduction of stearic acid. Conversion on pure m-ZrO₂ is 1.3 times more active than on t-ZrO₂, whereas Ni/m-ZrO₂ is three times more active than Ni/t-ZrO₂. Although the hydrodeoxygenation of stearic acid can be catalyzed solely by Ni, the synergistic interaction between Ni and the ZrO₂ support causes the variations in the reaction rates. Adsorption of the carboxylic acid group on an oxygen vacancy of ZrO₂ and the abstraction of the α-hydrogen atom with the elimination of the oxygen atom to produce a ketene is the key to enhance the overall rate. The hydrogenated intermediate 1-octadecanol is in turn decarbonylated to heptadecane with identical rates on all catalysts. Decarbonylation of 1-octadecanol is concluded to be limited by the competitive adsorption of reactants and intermediate. The substantially higher adsorption of propionic acid demonstrated by IR spectroscopy and the higher reactivity to O₂ exchange reactions with the more active catalyst indicate that the higher concentration of active oxygen defects on m-ZrO₂ compared to t-ZrO₂ causes the higher activity of Ni/m-ZrO₂.

Supported MoS₂/γ-Al₂O₃ and Ni-MoS₂/γ-Al₂O₃ as well as unsupported Ni-MoS₂ were investigated in the hydrodenitrogenation (HDN) of quinoline in the presence of dibenzothiophene (DBT). The supported oxide catalyst precursors had a well-dispersed amorphous polymolybdate structure that led to the formation of a highly dispersed sulfide phase. In contrast, the unsupported catalyst precursor consisted of a mixture of nickel molybdate and ammonium nickel molybdate phases that formed stacked sulfide slabs after sulfidation. On all catalysts, the reaction pathway for the removal of N in quinoline HDN mainly followed the sequence quinoline1,2,3,4-tetrahydroquinolinedecahydroquinolinepropylcyclohexylaminepropylcyclohexenepropylcyclohexane. The hydrodesulfurization of DBT proceeded mainly by direct desulfurization towards biphenyl. For both processes, the activity increased in the order MoS₂/γ-Al₂O₃<Ni-MoS₂/unsupported<Ni-MoS₂/γ-Al₂O₃. The promotion of the MoS₂ phase with Ni enhances the activity of the unsupported catalyst to a greater extent than the supported one. However, the multiply stacked unsupported Ni-MoS₂ exhibited lower rates than Ni-MoS₂/γ-Al₂O₃ because of its lower dispersion.

The synthesis of methanethiol from CS₂ catalyzed by Ni-, Co-, or K-modified MoS₂/SiO₂ through the sequence CS₂CH₃SHCH₃SCH₃ (DMS) has been studied. CS₂ is readily hydrogenated to CH₃SH, whereas CH₃SH and DMS decompose to CH₄ at high CS₂ conversions and temperatures. Thus, very high yields of CH₃SH can be obtained on all the catalysts. The addition of Co or Ni accelerates all reaction steps to allow the formation of CH₃SH under relatively mild conditions. On the contrary, K suppresses the formation of byproducts but also lowers the activity. The surface reaction proceeds through a series of hydrogen-addition steps, the rate-controlling step of which is the addition of the first H atom. H₂ adsorbs dissociatively, whereas CS₂ adsorbs strongly in a single active site prior to hydrogenation. The addition of Ni has a stronger enhancing effect on hydrogenation and accelerates the CS bond cleavage to a smaller extent than Co. Therefore, Ni leads to optimum CH₃SH yields and holds the best promise as promoter for the MoS₂ phase in the synthesis of methanethiol from CS₂.

Improved synthetic approaches for preparing small-sized Ni nanoparticles (d=3 nm) supported on HBEA zeolite have been explored and compared with the traditional impregnation method. The formation of surface nickel silicate/aluminate involved in the two precipitation processes are inferred to lead to the stronger interaction between the metal and the support. The lower Brønsted acid concentrations of these two Ni/HBEA catalysts compared with the parent zeolite caused by the partial exchange of Brønsted acid sites by Ni²⁺ cations do not influence the hydrodeoxygenation rates, but alter the product selectivity. Higher initial rates and higher stability have been achieved with these optimized catalysts for the hydrodeoxygenation of stearic acid and microalgae oil. Small metal particles facilitate high initial catalytic activity in the fresh sample and size uniformity ensures high catalyst stability.

The increasing demand for light olefins and the changing nature of basic feedstock has stimulated substantial research activity into the development of new process routes. Steam cracking remains the most industrially relevant pathway, but other routes for light-olefin production have emerged. Fluid catalytic cracking only produces ethene in minor concentrations. Challenged by marked catalyst deactivation, in contrast, catalytic dehydrogenation ethane up opens a more selective route to ethene. The oxidative dehydrogenation (ODH) of ethane, which couples the endothermic dehydration of ethane with the strongly exothermic oxidation of hydrogen, would potentially be the most attractive alternative route because it avoids the need for excessive internal heat input, but also consumes valuable hydrogen. In this Review, the current state of the ODH of ethane is compared with other routes for light-olefin production, with a focus on the catalyst and reactor system variants. New catalyst systems and reactor designs have been developed to improve the industrial competitiveness of the ODH reaction of ethane. The current state of our fundamental understanding of the ODH of light alkanes, in particular in terms of catalyst and reactor development, is critically reviewed. The proposed mechanisms and the nature of the active site for the ODH reaction are described and discussed in detail for selected promising catalysts. The reported catalytic performance and the possible limitations of these ODH catalysts will be examined and the performance of the emerging approaches is compared to the currently practiced methods.

The mechanism of the catalytic reduction of palmitic acid to n-pentadecane at 260 °C in the presence of hydrogen over catalysts combining multiple functions has been explored. The reaction involves rate-determining reduction of the carboxylic group of palmitic acid to give hexadecanal, which is catalyzed either solely by Ni or synergistically by Ni and the ZrO₂ support. The latter route involves adsorption of the carboxylic acid group at an oxygen vacancy of ZrO₂ and abstraction of the α-H with elimination of O to produce the ketene, which is in turn hydrogenated to the aldehyde over Ni sites. The aldehyde is subsequently decarbonylated to n-pentadecane on Ni. The rate of deoxygenation of palmitic acid is higher on Ni/ZrO₂ than that on Ni/SiO₂ or Ni/Al₂O₃, but is slower than that on H-zeolite-supported Ni. As the partial pressure of H₂ is decreased, the overall deoxygenation rate decreases. In the absence of H₂, ketonization catalyzed by ZrO₂ is the dominant reaction. Pd/C favors direct decarboxylation (−CO₂), while Pt/C and Raney Ni catalyze the direct decarbonylation pathway (−CO). The rate of deoxygenation of palmitic acid (in units of mmol mol_{total metal}⁻¹ h⁻¹) decreases in the sequence r_(Pt black)≈r_(Pd black)>r_(Raney Ni) in the absence of H₂. In situ IR spectroscopy unequivocally shows the presence of adsorbed ketene (CCO) on the surface of ZrO₂ during the reaction with palmitic acid at 260 °C in the presence or absence of H₂.

Au supported on CeO₂ prepared by deposition–precipitation with urea leads to a basic catalyst. Au acts in two ways as surface modifier. First, Au selectively interacts with Ce⁴⁺ cations by either blocking access to or reducing Ce⁴⁺ to Ce³⁺. Second, the resulting Au atoms (presumably as Au⁺ ions) act as soft, weak Lewis acid sites stabilizing carbanion intermediates and enhancing hydride abstraction in the dehydrogenation of alcohols. In consequence, the thus-synthesized basic catalyst catalyzes the dehydrogenation of propan-2-ol to acetone with high efficiency and without notable deactivation. Additionally, the dehydration pathway of propan-2-ol is eliminated, as Au also quantitatively blocks access to strongly acidic Ce⁴⁺ ions or reduces them to Ce³⁺.

Potassium-doped MoS₂ catalysts supported on Al₂O₃ were synthesized, characterized by using atomic absorption spectroscopy, N₂ physisorption, NO adsorption, X-ray diffraction, temperature-programmed sulfidation, and Raman spectroscopy, and tested in the synthesis of methanethiol from carbonyl sulfide (COS) and H₂. The results revealed that two phases, pure MoS₂ and potassium-decorated MoS₂ (formed at high potassium loadings), were present in the active catalysts. The main effect of potassium during sulfidation and during the catalytic reaction was to increase the mobility of surface oxygen or sulfur atoms. Thus, potassium promoted the disproportionation of COS to CO₂ and CS₂ and the production of CO from CO₂. Additionally, potassium cations hindered the reductive decomposition of COS to CO and H₂S and the hydrogenolysis of methanethiol to methane. Mars–van Krevelen-type mechanisms were proposed to explain the disproportionation of COS on alumina and on the MoS₂ phases. The catalytic site in the potassium-decorated MoS₂ phase was proposed to include a potassium cation as adsorption site.

The products of base-catalyzed liquid-phase hydrolysis of lignin depend markedly on the operating conditions. By varying temperature, pressure, catalyst concentration, and residence time, the yield of monomers and oligomers from depolymerized lignin can be adjusted. It is shown that monomers of phenolic derivatives are the only primary products of base-catalyzed hydrolysis and that oligomers form as secondary products. Oligomerization and polymerization of these highly reactive products, however, limit the amount of obtainable product oil containing low-molecular-weight phenolic products. Therefore, inhibition of concurrent oligomerization and polymerization reactions during hydrothermal lignin depolymerization is important to enhance product yields. Applying boric acid as a capping agent to suppress addition and condensation reactions of initially formed products is presented as a successful approach in this direction. Combination of base-catalyzed lignin hydrolysis with addition of boric acid protecting agent shifts the product distribution to lower molecular weight compounds and increases product yields beyond 85 %.

Composite films with low dielectric constants (k) containing micro- and mesopores are synthesized from precursor solutions for the preparation of mesoporous silica and ethanolic suspensions of silicalite-1 nanoparticles. The material contains silicalite-1 nanoparticles (include nanocrystals and nanoslabs/intermediates) embedded in a randomly oriented matrix of highly porous mesoporous silica. Micropores result from the incorporated silicalite-1 nanoparticles, while decomposition of the porogen F127 leads to additional mesopores. The porosity of the composite films increases from 9 to 60% with the increase in porogen loading, while in parallel the elastic modulus and hardness decrease. The elastic moduli of the films are in the range of 13–20 GPa. Hydrophobic surfaces of the composite films are obtained by introducing methyl triethoxysilane during the preparation of both precursor solutions, leading to the incorporation of CH₃ groups in the final composite films. These methyl groups are stable up to at least 500 °C. A low k value of approximately 2 is observed for films cured at 400 °C in N₂ flow, which is ideal for removing templates without decomposing methyl groups. Due to the intrinsic hydrophobicity of the material, post-silylation is not required rendering the composite films attractive candidates for future low k materials.